Children under the age of 1 year with a unilateral hearing loss and the fitting of technical devices (e.g. hearing aids)

There is well proven data that in case a bi-aural fitting is indicated but one ear is neglected, the hearing process of the unattended side will be deprived. But until now there is no sufficient data that with UHL a very early hearing aid fitting (within the first 6 months of life) makes a difference on the future maturation of the auditory pathways.

Taking in account the cost of effort and stress for the family that is connected with any hearing-aid fitting in the first months of life and regarding the diagnostic uncertainties in a number of cases of mild to moderate hearing-losses the BIAP commission suggests as a compromise a start of a hearing aid fitting within the first 12 months of life (instead of a recommended start with in the first 6 months with bilateral losses).

In case of a hearing aid fitting the same principals should be respected as with bilateral fittings (see Recom. 06-11). For the evaluation of a hearing aid benefit audiometric test should include a proper masking of the normal hearing ear when tolerated by the child. Also the use of specially designed questionnaires[1] can be recommended.

The hearing-aid fitting should be only finalized, if a sufficient acceptance of the hearing-aid by the child and the parents and a daily wearing of the hearing-aid is confirmed.

A hearing aid fitting on the hearing impaired ear may be beneficial and may lead/reinstate to a stereophonic as well as a directional hearing. (In case of a unilateral hearing loss of less than 30 dB a benefit of a hearing aid can not be expected and even the loudness difference between the ears may be partly centrally compensated so that a directional hearing is still possible)

In some cases a hearing aid fitting may still be successful with hearing losses between 60-80dB especially when a recruitment is present or regarding some cases of a high frequency hearing loss.

the patient will not benefit from a hearing aid fitting on the hearing impaired ear, because it will not be possible to provide enough amplification so that a level of equal loudness can be achieved on both sides.

in school age a fitting of an FM-system might be useful to improve the signal to noise ratio in difficult listening situations (Recom 06-10 + annex FM)

a C.R.O.S.-hearing-aid can be useful for some hearing situations, if the user is able to activate or deactivate the system according to his or her actual hearing situation. Especially in a diffuse noisy sound field the noise may be picked up by the C.R.O.S. microphone in a way that it can partially mask the speech information which the hearing impaired person tries to pick up with his/her good ear. Because a C.R.O.S. hearing aid cannot reinstate a true stereophonic hearing, using a C.R.O.S hearing-aid in a diffuse noisy sound field may prevent the benefit, the hearing impaired person might have without the hearing-aid by directing his/her good ear to the sound source. Therefore a tryout of a C.R.O.S. fitting should be restricted to older children (teenagers), who are able to cooperate and use the C.R.O.S technique selectively for special hearing situations (these considerations also apply for a transcranial C.R.O.S.-BAHA).

A bone conduction hearing aid with the microphone and the bone conductor both on the impaired side may be useful. The bone conductor + the hearing aid can be fixed with a metal bracket, a headband, a special cap or at the age of more than 5-6years a bone anchored hearing aid might be suitable. (If there exists still a small part of the external ear canal one should also try an air conduction hearing aid.)

Concerning the age at the time of the fitting, one should consider the mechanical difficulties when fitting a bone conduction hearing aid to a very young child, therefore a start of the fitting within (before/at the end of) the first year of life should be feasible and sufficient.

Information about additional technical considerations in later years

FM-systems also without the use of a hearing aid may improve the signal to noise ratio in noisy hearing situations (i.e. school) (Recom. 06-10).

Until recently most children with a unilateral hearing loss were diagnosed well beyond the age of 6 years and already attending school. With a universal newborn hearing screening program in place using a bilateral up to date hearing screening technique, bilateral as well as unilateral hearing losses are diagnosed within the first few months of life. This requires new and different concepts for the assessment, counselling and rehabilitation of those with a unilateral hearing loss.

Effects of a unilateral hearing loss

Neither audiologists or otolaryngologists nor paediatricians were usually concerned over unilateral hearing losses, other than to identify its aetiology. They also were assuring the parents that there was no handicap. According to their experience a unilateral hearing loss had no effect on the speech and language development of these children.

In contrast to this opinion several studies between 1986 and 1988 show that children with an unilateral hearing loss bear a more than ten times higher risk to fail at least one grade in school. These failures are related to the fact that these children do experience problems in their directional hearing and consequently in their ability to understand speech in noisy situations, as in a regular classroom. These studies additionally name attention and concentration deficits, getting tired in demanding listening situations and a loss of self confidence due to insecurity. Because of the difficulties in directional hearing safety problems for example in the traffic can not be ruled out.

From a neurophysiological standpoint it’s also well documented for bilateral hearing losses that if one ear is not integrated in the hearing process because only one ear is fitted with an hearing aid, that may lead to deprivation of the unfitted ear.

Epidemiology

In various publications one can find different prevalence numbers of unilateral hearing losses at the time of birth. Different hearing screening projects in Germany show that around a quarter of the hearing impaired babies identified through NHS have unilateral hearing losses

There are also estimates that between 5-10% of unilateral hearing losses are progressive and some of them also turning into a bilateral loss.

The causes, the configuration and the severity of the hearing losses seem to be equally distributed comparing unilateral and bilateral hearing losses.

Assessment

a. Anamnesis

Taking the case history, special attention should be given to:

1. Symptoms that can be primarily related to a unilateral hearing loss like:

being able to telephone properly only on one of the ears

not responding to a wake–up call if sleeping on the good ear

reduced directional hearing (being unable to locate a caller in a different room at home or an approaching car in the traffic)

hearing especially bad when having a middle ear ventilation disorder on the good ear

2. Some more unspecific symptoms which maybe connected to unilateral losses like:

attention and concentration difficulties

school problems, missing information, distracting other pupils

3. Some causes that may lead to a unilateral hearing loss:

family history

pregnancy (CMV.. ), birth, neonatal period

infections during childhood (like mumps ......)

accidents (skull fractures)

malformations of the external ear

acoustic trauma

b. Examination/Hearing testing

The testing of unilateral hearing losses with young children may be especially difficult because of problems using masking procedures. With babies the diagnostic process may start with a NHS. To find unilateral losses through NHS a protocol that screens each ear separately is necessary. The subsequent audiological diagnostic procedures must follow the same strict time table as with bilateral losses, so that also unilateral losses are diagnosed within the first 6 month of age. All families with a child with a unilateral hearing loss need a thorough counseling by an expert in pediatric audiology. Regardless of further therapeutic procedures a control hearing test should be performed every 3 month during the first year of life then twice a year up to kindergarten, then once a year at least until the end of primary school.

To assess unilateral hearing losses the audiometric testing should regard the best practice recommendations for bilateral losses and additionally it has to factor in:

measure the hearing threshold always separately on each side including an airconduction and a bone conduction threshold

using consequent masking with all the hearing test procedures (ABR, VRA, ....),

aided thresholds on the impaired side can only yield valid results, if the normal hearing ear is properly masked with a headphone

insert earphones should be preferred (because of a greater interaural attenuation)

in case of a progressive or newly developed unilateral hearing loss a MRI scan and a vestibular testing is recommended

Concerning therapeutic procedures a categorization of unilateral hearing losses in the following subgroups is helpful (also see the annex on hearing aid fitting):

When the diagnosis of an unilateral deafness is established, in particular within the framework of a systematic newborn hearing screening program the BIAP recommends the installation of an early parental counselling and support by an expert in paediatric audiology. Also reassuring the parents, that almost all children will learn to listen and to peak like all other children despite their unilateral hearing loss, therefore any overprotection should be avoided.

The program of accompanying parents aims at:

to listen and to reassure the parents confronted with the diagnosis

to allow them to express their possible concerns or guilt

to meet their need for information

It will be necessary to explain to the parents the importance:

of a regular monitoring of the child’s hearing in both ears (probably at 6 month, 1year and if not progressive then at least once a year) by an ORL or paediatric audiologist

of a monitoring of the development of the prelinguistic communication skills and consecutively the development of speech and language (assessment during the first 3 years, see CT 24)

of a need to adapt their communication behaviour to the child’s needs

Then, it will be necessary to recommend:

an information of the teacher in kindergarten and in school

an evaluation of the first steps of knowledge acquisition in school

an information of potential risks of the practice of extreme sports (risk of head trauma, hypoxia, barotrauma ...).

Explaining the effects of a unilateral hearing loss the information for the parents and the teachers should include the following considerations:

Loss of directional hearing

Safety concerns in the traffic

Orientations problems when reacting to calling

Problems to hear and to understand in noisy situations, especially in kindergarten, school (+ entitlement for special integration services)

Adaptation of the acoustical environment to optimize the auditive reception in every communication situation to enhance speech understanding: e.g. to place the child well in regard to its best ear in the classroom.

As it is no longer a question whether a UNHS is feasible even on a national level, indicators show that a rehabilitation program including the fitting of hearing aids starting before 6 months of age can improve communication skills that are near the lower limit of a normal hearing child.

Yet the preconditions for this goal can only be achieved if UNHS interacts and is embedded in a multidisciplinary framework of audiological, medical, therapeutical and pedagogical services (14-1 bis) specialised in working with babies and their families (25-1, 25-2).

BIAP therefore endorses UNHS and encourages its member organisation to set up and promote a framework of multidisciplinary cooperation starting with an early identification by UNHS and continuing with a well founded early diagnosis. This will ensure an early rehabilitation before 6 months of age.

Family support (learning to live with the diagnosis + adapting to the new demands and new social circumstances):parental guidance (25/1, 25/2, 21), parent support group, early interventionist, social services

further interdisciplinary assessment to determine the origin of the hearing loss and/or to rule out other disabilities: e.g. paediatrician, geneticist ….

The rehabilitation requires a multidisciplinary approach (*) starting as soon as possible but well before 6 months of age

Early intervention / early promotion of communication skillse.g. speech therapist, special pedagogue, early interventionist, psychologist ….

When ever possible the UNHS should work closely together with other already existing neonatal screening programs, such as the metabolic screening, as all the programs require a similar procedure and assessment of tracking patients:Data (IT) management, public health services, quality management services

Continuing the existing hearing “screening” programs especially for children at risk and for the late onset hearing losses :

Paediatrician, ENT, paediatric audiologist

When establishing an early intervention program founded on a UNHS, all the professionals involved are confronted with new challenges like further training needs as well as the need to change and adapt pre-existing service practices like:

Adapting and refining early intervention procedures:informing about and providing unbiased intervention options, supporting the psychological strains of the family …

Services should only be provided by specialised professionals and institutions dedicated to cooperate with one another within a common protocol. Well organised ways of information exchange and feedback (including parent organisations) will help overcome initial pitfalls and will be a fundamental safeguard and keystone for an overall and long-term success of the whole UNHS and early rehabilitation program.

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The recommendation was approved by the general assembly of the BIAP after the validation by the national committees, 2007 in Rhodos (Greece)